A magnetic storage device configured to store therein information by using magnetization reversal by magnetic fields of electric currents is manufactured by using a semiconductor wafer (hereinafter, simply referred to as “wafer”) in which various layers are layered and etched in a desired shape. One of the various layers of the magnetic storage device is a platinum-manganese (Pt—Mn) layer containing platinum (Pt) as a magnetic material. It is known that platinum is one of materials that are difficult to be etched.
As a method for etching the platinum-manganese layer, there has been known a method for physically etching the platinum-manganese layer by an ion milling process, for example, a sputtering process using argon (Ar) cations of high energy. In the ion milling process, cations are projected to a mask film and to the platinum-manganese layer with high energy. As a result, it is difficult to obtain selectivity between the mask film and the platinum-manganese layer. Further, a pattern shape of the mask film is damaged early, and, thus, a hole or a trench formed by the etching process has a sidewall of a tapering shape (see, for example, Non-Patent Document 1).
Therefore, there has been suggested a method for chemically etching the platinum-manganese layer by an etching gas containing a halogen gas of high reducibility (see, for example, Patent Document 1).
Non-Patent Document 1: “Dry etching of high-k materials” of Ono Koichi, Takahashi Kazuo, and Erikuchi Koji: Journal of Plasma Fusion Research, Vo1.85, No. 4 (2009), pp. 185-192, issued on January 2009
Patent Document 1: Japanese Patent Laid-open Publication No. 2006-060172
However, since the halogen gas generates strong acids, there is a problem that corrosion of the magnetic material itself or components of a substrate processing apparatus becomes accelerated.